addEdit

The last edit added to this CompoundEdit
is given a chance to addEdit(anEdit).
If it refuses (returns false), anEdit is
given a chance to replaceEdit the last edit.
If anEdit returns false here,
it is added to edits.

the value from the defaults table with key
AbstractUndoableEdit.undoText, followed
by a space, followed by getPresentationName
unless getPresentationName is "" in which
case, the defaults value is returned alone.

the value from the defaults table with key
AbstractUndoableEdit.redoText, followed
by a space, followed by getPresentationName
unless getPresentationName is "" in which
case, the defaults value is returned alone.